Microglia states and nomenclature: A field at its crossroads
Authors listRosa C Paolicelli Amanda Sierra Beth Stevens Marie-Eve Tremblay Adriano Aguzzi Bahareh Ajami Ido Amit Etienne Audinat Ingo Bechmann Mariko Bennett Frederick Bennett Alain Bessis Knut Biber Staci Bilbo Mathew Blurton-Jones Erik Boddeke Dora Brites Bert Brône Guy C Brown Oleg Butovsky Monica J Carson Bernardo Castellano Marco Colonna Sally A Cowley Colm Cunningham Dimitrios Davalos Philip L De Jager Bart De Strooper Adam Denes Bart JL Eggen Ukpong Eyo Elena Galea Sonia Garel Florent Ginhoux Christopher K Glass Ozgun Gokce Diego Gomez-Nicola Berta González Siamon Gordon Manuel B Graeber Andrew D Greenhalgh Pierre Gressens Melanie Greter David H Gutmann Christian Haass Michael T Heneka Frank L Heppner Soyon Hong David A Hume Steffen Jung Helmut Kettenmann Jonathan Kipnis Ryuta Koyama Greg Lemke Marina Lynch Ania Majewska Marzia Malcangio Tarja Malm Renzo Mancuso Takahiro Masuda Michela Matteoli Barry W McColl Veronique E Miron Anna Victoria Molofsky Michelle Monje Eva Mracsko Agnes Nadjar Jonas J Neher Urte Neniskyte Harald Neumann Mami Noda Bo Peng Francesca Peri V Hugh Perry Phillip G Popovich Clare Pridans Josef Priller Marco Prinz Davide Ragozzino Richard M Ransohoff Michael W Salter Anne Schaefer Dorothy P Schafer Michal Schwartz Mikael Simons Cody J Smith Wolfgang J Streit Tuan Leng Tay Li-Huei Tsai Alexei Verkhratsky Rommy von Bernhardi Hiroaki Wake Valérie Wittamer Susanne A Wolf Long-Jun Wu Tony Wyss-Coray
Microglial research has advanced considerably in recent decades yet has been constrained by a rolling series of dichotomies such as "resting versus activated" and "M1 versus M2." This dualistic classification of good or bad microglia is inconsistent with the wide repertoire of microglial states and functions in development, plasticity, aging, and diseases that were elucidated in recent years. New designations continuously arising in an attempt to describe the different microglial states, notably defined using transcriptomics and proteomics, may easily lead to a misleading, although unintentional, coupling of categories and functions. To address these issues, we assembled a group of multidisciplinary experts to discuss our current understanding of microglial states as a dynamic concept and the importance of addressing microglial function. Here, we provide a conceptual framework and recommendations on the use of microglial nomenclature for researchers, reviewers, and editors, which will serve as the foundations for a future white paper.